Desert Catacombs

Desert Catacombs are a tomb located in the middle on Route 11. This place is home to Unown and has many passages expressed in Unown text, revealing the history of Roria and how Hoopa destroyed the region by manipulating one of the kings.

Unown Passages
"[I] To those whom enter this sacred place, be warned. This chamber is not bound by the laws of space and time. These halls are now channels to other realms. What is left here is a reminder of destruction first came from this place."

"[II] There was once a time of great peace in this land. The King once ruled righteously. In that time, these catacombs were used for summoning rituals. We communicated here with our ancestors beyond this realm. That was before The Evil Djinn, Hoopa, appeared."

"[III] The Evil Djinn appeared through these halls from another world during a ritual. Hoopa was the first Pokémon to appear from this place. It was its power to travel to new worlds. It escaped into our world and captured the king's attention. The king was fascinated by Hoopa. Hoopa would soon corrupt the mind of our great king, leading him to rule wickedly. The Evil Djinn did not stop there. It caused widespread destruction across our land. The people of our land prayed for help. That was when Arceus appeared."

"[IV] Arceus answered the prayers of people. Using its power of creation, Arceus gave us the key and the bottle. With them, we were able to imprison Hoopa on the crescent-shaped island off the east coast of our land."

"[V] The Evil Djinn now lays locked away deep within that island. The key to its chamber was taken and hidden in the heart of our land, deep in a cave. Let this be a warning, the beast shall remain locked away. Releasing Hoopa will surely result in catastrophic destruction."

"[VI] These ruins now serve to remind us of our past. Since Hoopa appeared through these halls, the barrier between our world and others has been weakened. Other strange Pokémon have been known to appear here from other worlds, but none with destructive intent like Hoopa."

"[VII] Our kingdom had already been destroyed by the wicked king before Hoopa had been found. The reign of the kings in our land ended shortly after these events transpired. We now rebuild all that was lost and give this land a new name -- Roria."

Keys For Time and Space
In the middle room of basement, there are 2 small pedestals, requiring the keys for Time and Space to be placed respectively:

"A key representing Time/Space shall be placed here."

It is currently unknown if this room relates to Legendary Pokémon encounter later on.